Which physical findings are characteristic of Riehl melanosis (pigmented contact dermatitis)?

Updated: May 27, 2021
  • Author: Elizabeth K Satter, MD, MPH; Chief Editor: William D James, MD  more...
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Answer

Many cases are preceded by mild erythema, edema, and pruritus, [5] followed by a diffuse-to-reticulated pattern of hyperpigmentation. The pigmentation varies dependent upon the causal agent and can be brown, slate-gray, gray-brown, red-brown, or blue-brown. [5, 7, 18]

Several case reports published in 2017 describe patients who presented with pigmented contact dermatitis secondary to balsam of Peru and/or fragrances that was associated with reversible alopecia if the trigger was identified early and removed. [29, 30]

The site of pigmented contact dermatitis also depends on the allergen responsible. Pigmented cosmetic dermatitis more commonly involves the face, whereas pigmented contact dermatitis due to textiles more often involves the anterior thighs or the axilla, with sparing of the axillary vault. [7] Additionally, hyperpigmentation is most pronounced in individuals with darker complexions.

UV exposure may contribute to the hyperpigmentation in select cases, which is supported by the fact that some of the chemicals implicated are known photosensitizers, and, in these cases, the pigmentation appears to be most pronounced in sun-exposed areas. [5, 7]


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